1. Field of the Invention
This invention pertains to motion detectors and, more particularly to motion detectors with adjustable wide viewing areas.
2. Description of the Related Art
Motion detector lighting controls that include an infrared sensor box and a pair of lamp holders, all rotatably mounted to a mounting box, have been known for years. When an infrared emitting object, such as an animal, enters the viewing zone of the infrared sensor located inside the infrared sensor box, the lamps connected to the infrared sensor are automatically activated to illuminate the desired area at which the lamps are aimed. When the object leaves the viewing zone, the lamps automatically turn off after a pre-determined amount of time.
One problem with such controls is that the viewing angle of the sensor box is limited to approximately fifty (50) feet on both sides of the normal axis of the lens of the sensor box (110 degrees total). When the infrared emitting object approaches the light fixture from an angle outside the viewing zone, the lamps are not automatically activated.
U.S. Pat. Nos. 5,418.368 and 5,453,622 disclose wide-angle motion detectors designed to extend the viewing zone greater than 180 degrees by using a plurality of inclined infrared mirror faces designed to direct sufficient intensity of radiation to the sensor from outlying angles. Such detectors use two or more infrared-reflecting faces which are positioned close to, and overlie at least a portion, of the sensor. The reflecting faces are configured so that their ends proximal to the sensor overlie the sensor at its midpoint and the faces extend from the mid-point in different directions away from one another to reflect radiation to the sensor from different sides of the sensor. Unfortunately, the lenses and reflective faces used on such detectors may become dirty or fogged over time, which reduces sensor operation
Another drawback with using wide-angle single detectors is that the user is unable to split the coverage area into smaller coverage areas. In some instances motion detectors are used in a long narrow environment such as a walkway, where they are used to activate a floodlight, mounted on an adjacent wall, when an object enters the walkway from either end. Since an object may enter the walkway from either end, a wide-angle detector must be aimed at the middle axis between the two ends so that motion at each end of the walkway is detected. Motion detection near or along the middle axis is not necessary. In other instances, it may be desirable to exclude a middle section of the wide coverage from detection.
Another drawback with single wide angle motion detectors is that their viewing fields have uniform height or depth. The heights or depths of sections in their viewing fields can not be selectively adjusted. Such an adjustment feature would be desireable, for example, when detecting movement in a stairway or its lower landing area.
It is an object of the present invention to provide a motion detector assembly with adjustable wide viewing area.
It is another object of the present invention to provide such a motion detector assembly in which the arc and height of selected sections of the viewing areas may be independently adjusted by the user.
It is a further object of the invention to provide such a motion detector assembly that is less likely to fail over time due to dirty or fogged conditions.
These and other objects of the invention which will become apparent are met by an improved dual head motion detector assembly comprising an independently adjustable main motion sensor head and an independently adjustable secondary motion sensor head both pivotally mounted to a mounting box. Both the main motion sensor head and the secondary motion sensor head contain standard infrared motion sensors each with an approximate 110-degree viewing zone. The two motion sensors are both connected to a control panel located in the main motion sensor head with on/off switch and sensitivity control switches externally mounted thereto. The control panel is connected between at least one lamp socket and to an outside 110-volt electric circuit. When an infrared-emitting object passes into one or both viewing zones of the two motion sensors, the circuit between the control panel and the lamp socket opens thereby activating the bulb connected to the lamp socket.
When a wide, combined viewing area is desired, the main and secondary motion sensor heads are pivotally adjusted on the mounting box so that their separate viewing zones slightly overlap thereby providing a total coverage zone of approximately 330 degrees. The main and secondary motion sensor heads may be independently twisted towards their desired viewing areas and independently elevated to obtain different viewing areas depths. Also, both the main and secondary motion sensor heads use single lens infrared sensors rather than multiple lens or mirror sensors thereby making them less susceptible to dirt or fog.